Identityconsole: Host mismatch

OES24.4:

https://<FQDN:9010/identityconsole/> shows a "Host mismatch". (regardeless of the browser)

I checked the certificate and found that the FQDN is listed as common name and as SAN in the certificate. (It is the 'normal' server cert for a OES-Server)

Any hints?